Near-infrared fluorescent probe visual detection of Hg2+ and its application in biological system and ecological system.

Mercury ion (Hg2+), a heavy metal cation with greater toxicity, is widely present in the ecological environment and has become a serious threat to human health and environmental safety. Currently, developing a solution to simultaneously visualize and monitor Hg2+ in environmental samples, including water, soil, and plants, remains a great challenge. In this work, we created and synthesized a near-infrared fluorescent probe, BBN-Hg, and utilized Hg2+ to trigger the partial cleavage of the carbon sulfate ester in BBN-Hg as a sensing mechanism, and the fluorescence intensity of BBN-Hg was significantly enhanced at 650 nm, thus realizing the visualization of Hg2+ with good selectivity (detection limit, 53 nM). In live cells and zebrafish, the probe BBN-Hg enhances the red fluorescence signal in the presence of Hg2+, and successfully performs 3D imaging on zebrafish, making it a powerful tool for detecting Hg2+ in living systems. More importantly, with BBN-Hg, we are able to detect Hg2+ in actual water samples, soil and plant seedling roots. Furthermore, the probe was prepared as a test strip for on-site determination of Hg2+ with the assistance of a smartphone. Therefore, this study offers an easy-to-use and useful method for tracking Hg2+ levels in living organisms and their surroundings.

Adsorption of haem by magnetic chitosan microspheres: Optimal conditions, adsorption mechanisms and density functional theory analyses.

Magnetic chitosan microspheres (Al@CTS@Fe3O4) were prepared for haem separation via chemical cross-linking of chitosan, Fe3O4 and AlCl3·6H2O. The properties of the Al@CTS@Fe3O4 microspheres were investigated through techniques including XRD, TEM, FTIR, BET analysis, SEM, TG, VSM, XPS and pHpzc analysis. The haem adsorption of Al@CTS@Fe3O4 was optimized via a Box-Behnken design (BBD) with three operating factors: Fe3O4 dose (0.5-1.3 g), AlCl3·6H2O concentration (0.25-1.25 mol/L) and glutaraldehyde dose (2-6 mL). The optimal haem adsorption effect was achieved with 1.1 g of Fe3O4, 0.75 mol/L AlCl3·6H2O, and 3 mL of glutaraldehyde. The adsorption kinetics and isotherms demonstrated that haem adsorption by the Al@CTS@Fe3O4 microspheres was best described by the pseudo-second-order model. The maximum adsorption capacity is 33.875 mg/g at pH 6. After six adsorption-desorption cycles, the removal of haem still reached 53.83 %. The surface adsorption mechanism of haem on Al@CTS@Fe3O4 can be attributed to electrostatic, hydrogen bonding, and n-π interactions. Thermodynamic calculations indicated that the adsorption process is spontaneous, with the microspheres preferentially accepting electrons and haem preferentially providing electrons. Consequently, the Al@CTS@Fe3O4 microspheres exhibit considerable potential as adsorbents for haem separation.

In vitro Synergistic and Bactericidal Effects of Aztreonam in Combination with Ceftazidime/ Avibactam, Meropenem/Vaborbactam and Imipenem/Relebactam Against Dual-Carbapenemase-Producing Enterobacterales.

Objective: Our aim was to elucidate the resistance mechanisms and assess the combined synergistic and bactericidal activities of aztreonam in combination with ceftazidime/avibactam (CZA), meropenem/vaborbactam (MEV), and imipenem/relebactam (IMR) against Enterobacterales strains producing dual carbapenemases. Methods: Species identification, antimicrobial susceptibility testing and determination of carbapenemase type were performed for these strains. Plasmid sizes, plasmid conjugation abilities and the localization of carbapenemase genes were investigated. Whole-genome sequencing was performed for all strains and their molecular characteristics were analyzed. In vitro synergistic and bactericidal activities of the combination of aztreonam with CZA, MEV and IMR against these strains were determined using checkerboard assay and time-kill curve assay. Results: A total of 12 Enterobacterales strains producing dual-carbapenemases were collected, including nine K. pneumoniae, two P. rettgeri, and one E. hormaechei. The most common dual-carbapenemase gene pattern observed was bla (KPC-2+NDM-5) (n=4), followed by bla KPC-2+IMP-26 (n=3), bla (KPC-2+NDM-1) (n=2), bla (KPC-2+IMP-4) (n=1), bla (NDM-1+IMP-4) (n=1) and bla (KPC-2+KPC-2) (n=1). In each strain, the carbapenemase genes were found to be located on two distinct plasmids which were capable of conjugating from the original strain to the receipt strain E. coli J53. The results of the checkerboard synergy analysis consistently revealed good synergistic effects of the combination of ATM with CZA, MEV and IMR. Except for one strain, all strains exhibited significant synergistic activity and bactericidal activity between 2 and 8 hours. Conclusion: Dual-carbapenemase-producing Enterobacterales posed a significant threat to clinical anti-infection treatment. However, the combination of ATM with innovative ß-lactam/ß-lactamase inhibitor compounds had proven to be an effective treatment option.

Endomembrane trafficking driven by microtubule growth regulates stomatal movement in Arabidopsis.

Microtubule-based vesicle trafficking usually relies upon kinesin and dynein motors and few reports describe microtubule polymerisation driving directional vesicle trafficking. Here we show that Arabidopsis END BINDING1b (EB1b), a microtubule plus-end binding protein, directly interacts with SYP121, a SNARE protein that mediates the trafficking of the K+ channel KAT1 and its distribution to the plasma membrane (PM) in Arabidopsis guard cells. Knockout of AtEB1b and its homologous proteins results in a modest but significant change in the distribution of KAT1 and SYP121 in guard cells and consequently delays light-induced stomatal opening. Live-cell imaging reveals that a portion of SYP121-associated endomembrane compartments co-localise with AtEB1b at the growing ends of microtubules, trafficking along with the growth of microtubules for targeting to the PM. Our study reveals a mechanism of vesicle trafficking driven by microtubule growth, which is involved in the redistribution of PM proteins to modulate guard cell movement.

CYP7B1 deficiency impairs myeloid cell activation in autoimmune disease of the central nervous system.

Dysregulation of cholesterol metabolism underlies neurodegenerative disease and is increasingly implicated in neuroinflammatory diseases, such as multiple sclerosis (MS). Cytochrome P450 family 7 subfamily B member 1 (CYP7B1) is a key enzyme in alternative cholesterol metabolism. A recessive mutation in the gene CYP7B1 is known to cause a neurodegenerative disease, hereditary spastic paraplegia type 5 and oxysterol accumulation. However, the role of CYP7B1 in neuroinflammation has been little revealed. In this study, we induced experimental autoimmune encephalomyelitis (EAE), as a murine model of MS, using CYP7B1 homozygous knockout (KO) mice. We found that CYP7B1 deficiency can significantly attenuate EAE severity. CYP7B1 deficiency is sufficient to reduce leukocyte infiltration into the central nervous system, suppress proliferation of pathogenic CD4+ T cells, and decrease myeloid cell activation during EAE. Additionally, live-animal imaging targeting translocator protein expression, an outer mitochondrial membrane protein biomarker of neuroinflammation, showed that CYP7B1 deficiency results in suppressed neuroinflammation. Using human monocyte-derived microglia-like cellular disease model and primary microglia of CYP7B1 KO mice, we also found that activation of microglia of CYP7B1 deficiency was impaired. These cumulative results suggest that CYP7B1 can regulate neuroinflammation, thus providing potential new targets for therapeutic intervention.

International operations and corporate R&D investment: Evidence from China.

This paper presents an examination of the relationship between international operations and corporate R&D investment. Using a large sample of Chinese listed firms for the 2009-2022 period and the ordinary least squares method, we find that international operations have a positive effect on corporate R&D investment. The finding remains valid after a battery of robustness tests. Mechanism tests show that international operations increase corporate R&D investment by diversifying product demand instead of increasing firms' international knowledge acquisition. This paper provides new evidence on the role of international operations in innovation activities.

Construction of Six-Membered Lactam and Lactone Structures via Ligand-Free Pd-Catalyzed C-H Activation/[5 + 1] Cyclization Carbonylation.

An approach for the ligand-free Pd-catalyzed C-H activation/[5 + 1] cyclization carbonylation by employing readily available ClCF2COONa as a carbonyl source via difluorocarbene transfer and hydrolysis has been developed. The current protocol enables us to obtain a series of carbonylation cyclization product benzopyranone and phenanthridinone derivatives in up to 91% yield with excellent functional group compatibility. This protocol has the advantages of mild reaction conditions, wide applicable substrates, and simple and safe operation and provides a new method for the synthesis of complex lactam and lactone compounds.

EXPRESS: Word length and frequency effects in natural Chinese reading: Evidence for character representations in lexical identification.

Word length and frequency are two of the "big three" factors that affect eye movements in natural reading (Clifton et al., 2016). Whilst these factors have been extensively investigated, all previous studies manipulating word length have been confounded with changes in visual complexity (longer words have more letters and are more visually complex). We controlled stroke complexity across one-character (short) and two-character (long) high- and low-frequency Chinese words (to avoid complexity confounds) and recorded readers' eye movements during sentence reading. Both word length and frequency yielded strong main effects for fixation time measures. For saccadic targeting and skipping probability, word length effects, but not word frequency effects, occurred. Critically, the interaction was not significant regardless of stroke complexity, indicating that word length and frequency independently influence lexical identification and saccade target selection during Chinese reading. The results provide evidence for character level representations during Chinese word recognition in natural reading.

Application of a hybrid-fruit-peel (HFP) coagulant in low carbon source wastewater treatment as an external carbon source.

The application of a hybrid-fruit-peel (HFP) coagulant used as an external carbon source (ECS) in both simulated water and real sewage having a low carbon source treated with sequencing batch reactor (SBR) was studied, compared with that of sodium acetate (NaAc). The impact of HFP on sludge properties (such as extracellular polymer substance (EPS), dehydrogenase activity (DHA), charged property, size, microscopic images and bacteria phase) was characterized. The results showed that as an ECS, HFP basically gave similar nitrogen removal to NaAc and also gave a similar developing trend of both dissolved oxygen (DO) and pH. HFP promoted more proliferation of microorganisms and posed higher levels of protein (PN) and polysaccharide (PS) than NaAc, but gave slightly lower DHA than NaAc. After HFP was added as an ECS, the types and quantities of microorganisms increased significantly, the effluent qualities were improved and the sludge size and extensibility became larger, which was conducive to direct contact and remove pollutants. HFP played a similar role to NaAc as ECS and can be used as a quality and slow-releasing ECS for low carbon source wastewaters.

The role of mitochondrial dysfunction in the association between trace metals and QTc prolongation in the aged population.

This study delves into the relationship between environmental metal exposure and QT interval corrected for heart rate (QTc) prolongation, a critical marker for cardiovascular risk in the elderly. Although the interplay between metal exposure and QTc prolongation is important for predicting sudden cardiac death, it remains underexplored. Our analysis of 6478 participants from the Shenzhen aging-related disorder cohort involved measuring urinary concentrations of 22 trace metals and using mitochondrial DNA copy number (mtDNA-CN) as an indicator of mitochondrial dysfunction. Utilizing Bayesian kernel machine regression, and structural equation modeling, we assessed the effects of mixed trace metals on QTc prolongation. Our findings indicated a direct association between certain metals (Sb, Cu, Zn) and a 7 % increase in QTc prolongation risk, while Li, V, and Rb were associated with a 5 % reduction in risk. Elevated levels of V, Ti, and Cr corresponded to higher mtDNA-CN. Notably, restricted cubic splines revealed a U-shaped, nonlinear relationship between mtDNA-CN and QTc prolongation. After adjusting for metal exposure, an inverse correlation was observed between mtDNA-CN and QTc prolongation, suggesting mitochondrial dysfunction as a partial mediator.

Structural analysis of the human C5a-C5aR1 complex using cryo-electron microscopy.

The complement system is a complex network of proteins that plays a crucial role in the innate immune response. One important component of this system is the C5a-C5aR1 complex, which is critical in the recruitment and activation of immune cells. In-depth investigation of the activation mechanism as well as biased signaling of the C5a-C5aR1 system will facilitate the elucidation of C5a-mediated pathophysiology. In this study, we determined the structure of C5a-C5aR1-Gi complex at a high resolution of 3 Å using cryo-electron microscopy (Cryo-EM). Our results revealed the binding site of C5a, which consists of a polar recognition region on the extracellular side and an amphipathic pocket within the transmembrane domain. Furthermore, we found that C5a binding induces conformational changes of C5aR1, which subsequently leads to the activation of G protein signaling pathways. Notably, a key residue (M265) located on transmembrane helix 6 (TM6) was identified to play a crucial role in regulating the recruitment of ß-arrestin driven by C5a. This study provides more information about the structure and function of the human C5a-C5aR1 complex, which is essential for the proper functioning of the complement system. The findings of this study can also provide a foundation for the design of new pharmaceuticals targeting this receptor with bias or specificity.

Direct Observations of Spontaneous In-Plane Electronic Polarization in 2D Te Films.

Single-element polarization in low dimensions is fascinating for constructing next-generation nanoelectronics with multiple functionalities, yet remains difficult to access with satisfactory performance. Here, spectroscopic evidences are presented for the spontaneous electronic polarization in tellurium (Te) films thinned down to bilayer, characterized by low-temperature scanning tunneling microscopy/spectroscopy. The unique chiral structure and centrosymmetry-breaking character in 2D Te gives rise to sizable in-plane polarization with accumulated charges, which is demonstrated by the reversed band-bending trends at opposite polarization edges in spatially resolved spectra and conductance mappings. The polarity of charges exhibits intriguing influence on imaging the moiré superlattice at the Te-graphene interface. Moreover, the plain spontaneous polarization robustly exists for various film thicknesses, and can universally preserve against different epitaxial substrates. The experimental validations of considerable electronic polarization in Te multilayers thus provide a realistic platform for promisingly facilitating reliable applications in microelectronic devices.

Efficient CdIn2S4/MgIn2S4 heterojunction for ultrasensitive detection of lung cancer marker neuron-specific enolase.

In this work, a photoelectrochemical (PEC) immunosensor was constructed for the ultrasensitive detection of lung cancer marker neuron-specific enolase (NSE) based on a microflower-like heterojunction of cadmium indium sulfide and magnesium indium sulfide (CdIn2S4/MgIn2S4, CMIS) as photoactive material. Specifically, the well-matched energy level structure and narrow energy level gradients between CdIn2S4 and MgIn2S4 could accelerate the separation of electron-hole (e--h+) pairs in the CMIS heterojunction to enhance the photocurrent of CMIS, which was increased 5.5 and 80 times compared with that of single CdIn2S4 and MgIn2S4, respectively. Meanwhile, using CMIS as photoactive material, increasing the biocompatibility by dropping Pt NPs on the surface of CMIS to immobilize the antibody through Pt-N bond. Fe3O4-Ab2, acting as the quencher, competitively consumes electron donors and absorbs light, leading to photocurrent quenching. With the increasing of quencher, the photocurrent decreased. Hence, the developed "signal-off" PEC immunosensor realized the trace detection of NSE within the range from 1.0 fg/mL to 10 ng/mL with a low detection limit of 0.34 fg/mL. This strategy provided a new perspective for establishing ternary metal sulfide heterojunction to construct PEC immunosensor for sensitive detection of disease biomarkers.

microRNAs in kidney diseases: Regulation, therapeutics, and biomarker potential.

MicroRNAs (miRNAs) are small, non-coding RNA molecules that play a crucial role in regulating gene expression by inhibiting the translation of their specific target messenger RNAs. To date, numerous studies have demonstrated changes in the expression of miRNAs in the kidneys throughout the progression of both acute kidney injury (AKI) and chronic kidney disease (CKD) in both human patients and experimental models. The role of specific microRNAs in the pathogenesis of kidney diseases has also been demonstrated. Further studies have elucidated the regulation of these microRNAs in diseased kidneys. Besides, certain miRNAs are detected in plasma and/or urine in kidney diseases and are potential diagnostic biomarkers. In this review, we provide an overview of recent developments in our understanding of how miRNAs contribute to kidney diseases. We also explore the potential of miRNAs as both biomarkers and therapeutic targets for these conditions, and highlight future research directions.

IL-2-armored peptide-major histocompatibility class I bispecific antibodies redirect antiviral effector memory CD8+ T cells to induce potent anti-cancer cytotoxic activity with limited cytokine release.

T cell engagers (TCEs) are becoming an integral class of biological therapeutic owing to their highly potent ability to eradicate cancer cells. Nevertheless, the widespread utility of classical CD3-targeted TCEs has been limited by narrow therapeutic index (TI) linked to systemic CD4+ T cell activation and aberrant cytokine release. One attractive approach to circumvent the systemic activation of pan CD3+ T cells and reduce the risk of cytokine release syndrome is to redirect specific subsets of T cells. A promising strategy is the use of peptide-major histocompatibility class I bispecific antibodies (pMHC-IgGs), which have emerged as an intriguing modality of TCE, based on their ability to selectively redirect highly reactive viral-specific effector memory cytotoxic CD8+ T cells to eliminate cancer cells. However, the relatively low frequency of these effector memory cells in human peripheral blood mononuclear cells (PBMCs) may hamper their redirection as effector cells for clinical applications. To mitigate this potential limitation, we report here the generation of a pMHC-IgG derivative known as guided-pMHC-staging (GPS) carrying a covalent fusion of a monovalent interleukin-2 (IL-2) mutein (H16A, F42A). Using an anti-epidermal growth factor receptor (EGFR) arm as a proof-of-concept, tumor-associated antigen paired with a single-chain HLA-A *02:01/CMVpp65 pMHC fusion moiety, we demonstrate in vitro that the IL-2-armored GPS modality robustly expands CMVpp65-specific CD8+ effector memory T cells and induces potent cytotoxic activity against target cancer cells. Similar to GPS, IL-2-armored GPS molecules induce modulated T cell activation and reduced cytokine release profile compared to an analogous CD3-targeted TCE. In vivo we show that IL-2-armored GPS, but not the corresponding GPS, effectively expands grafted CMVpp65 CD8+ T cells from unstimulated human PBMCs in an NSG mouse model. Lastly, we demonstrate that the IL-2-armored GPS modality exhibits a favorable developability profile and monoclonal antibody-like pharmacokinetic properties in human neonatal Fc receptor transgenic mice. Overall, IL-2-armored GPS represents an attractive approach for treating cancer with the potential for inducing vaccine-like antiviral T cell expansion, immune cell redirection as a TCE, and significantly widened TI due to reduced cytokine release.

Frequency-aware Feature Fusion for Dense Image Prediction.

Dense image prediction tasks demand features with strong category information and precise spatial boundary details at high resolution. To achieve this, modern hierarchical models often utilize feature fusion, directly adding upsampled coarse features from deep layers and high-resolution features from lower levels. In this paper, we observe rapid variations in fused feature values within objects, resulting in intra-category inconsistency due to disturbed high-frequency features. Additionally, blurred boundaries in fused features lack accurate high frequency, leading to boundary displacement. Building upon these observations, we propose Frequency-Aware Feature Fusion (FreqFusion), integrating an Adaptive Low-Pass Filter (ALPF) generator, an offset generator, and an Adaptive High-Pass Filter (AHPF) generator. The ALPF generator predicts spatially-variant low-pass filters to attenuate high-frequency components within objects, reducing intra-class inconsistency during upsampling. The offset generator refines large inconsistent features and thin boundaries by replacing inconsistent features with more consistent ones through resampling, while the AHPF generator enhances high-frequency detailed boundary information lost during downsampling. Comprehensive visualization and quantitative analysis demonstrate that FreqFusion effectively improves feature consistency and sharpens object boundaries. Extensive experiments across various dense prediction tasks confirm its effectiveness. The code is made publicly available at https://github.com/Linwei-Chen/FreqFusion.

High-level ceftriaxone resistance due to transfer of penA allele 60.001 into endemic gonococcal lineages in Hangzhou, China.

OBJECTIVES: Neisseria gonorrhoeae strains associated with the high-level ceftriaxone-resistant FC428 clone or containing its main resistance determinant, penA allele 60.001, have shown global transmission. In Hangzhou, China, 10% of the isolates were associated with the FC428 clone in 2019. Here, we investigated ceftriaxone resistance and the prevalence of FC428-associated strains in Hangzhou in 2020-22. METHODS: A total of 209 gonococcal isolates were investigated for antimicrobial susceptibility to ceftriaxone and other antibiotics by agar dilution method. Sequence types and penA alleles were determined by PCR and sequence analysis. RESULTS: Resistance to ceftriaxone (MIC > 0.125 mg/L) was observed for 16% (33/209) of the isolates, whereas 6.7% (14/209) of the isolates displayed high-level ceftriaxone resistance (MIC = 1 mg/L). These 14 high-level ceftriaxone-resistant isolates and another isolate displaying an MIC = 0.25 mg/L contained penA allele 60.001, with eight of these isolates, all from 2020 to 2021 belonging to MLST ST1903, the sequence type commonly associated with the original FC428 clone. Importantly, the six penA allele 60.001-containing isolates from 2022 belonged to MLST ST8123, ST7365 and ST7367, which are among the most frequently encountered sequence types found in China. Therefore, these results indicate that endemic lineages in China have acquired penA allele 60.001. CONCLUSIONS: Here, we report continued transmission of gonococcal strains associated with the FC428 clone or containing penA allele 60.001 in Hangzhou. A major concern for public health is the acquisition of penA allele 60.001 by successful endemic lineages, which might enhance the transmission of this high-level ceftriaxone resistance trait.

B-cell depletion limits HTLV-1-infected T-cell expansion and ameliorate HTLV-1-associated myelopathy.

OBJECTIVE: Human T-cell leukemia virus type 1-associated myelopathy (HAM) is a chronic, progressive, inflammatory disease with unclear pathogenesis and no effective treatments. We aimed to investigate a novel mechanistic theory and treat HAM patients with rituximab, which can deplete CD20+ B lymphocytes in circulation. METHODS: Single-cell RNA sequencing (scRNA-seq) data was analyzed to identify HTLV-1-associated B cells and their effect on T cells. An observational analysis of our HAM cohort was conducted to elucidate changes in the immunological microenvironment of these patients. Peripheral blood mononuclear cells (PBMC) from HAM patients were isolated to explore the efficacy of B cell depletion in vitro. To assess the effect of B-cell depletion on HAM patients, eligible participants in our cohort received rituximab therapy (NCT04004819). RESULTS: ScRNA-seq results suggest a significant effect of HTLV-1-associated B cells on T cells. Additionally, HTLV-1 was found to infect B cells and depletion of B cells inhibited the proliferation of T cells. Number of B cells in HAM patients had positive correlation with the proviral load and infected cell counts. Depletion of B cells led to a reduction in HTLV-1 proviral load in vitro. Furthermore, in clinical trial, 14 HAM patients were enrolled. Three patients (21.4%) who received rituximab failed to achieve remission, compared to 24 (85.7%) patients received any other therapy that failed to achieve remission. With a low level of circulating B cells, the proportion of Ki67-positive cells in CD4+ T cells fell. INTERPRETATION: This study provided evidence that depleting B-lymphocytes is an innovative strategy for treating patients with HAM and broadens the understanding of the role of B cells in infectious immunity.

Single-molecule sensing inside stereo- and regio-defined hetero-nanopores.

Heteromeric pore-forming proteins often contain recognition patterns or stereospecific selection filters. However, the construction of heteromeric pore-forming proteins for single-molecule sensing is challenging due to the uncontrollability of producing position isomers and difficulties in purification of regio-defined products. To overcome these preparation obstacles, we present an in situ strategy involving single-molecule chemical modification of a heptameric pore-forming protein to build a stereo- and regio-specific heteromeric nanopore (hetero-nanopore) with a subunit stoichiometric ratio of 3:4. The steric hindrance inherent in the homo-nanopore of K238C aerolysin directs the stereo- and regio-selective modification of maleimide derivatives. Our method utilizes real-time ionic current recording to facilitate controlled voltage manipulation for stoichiometric modification and position-based side-isomer removal. Single-molecule experiments and all-atom molecular dynamics simulations revealed that the hetero-nanopore features an asymmetric stereo- and regio-defined residue structure. The hetero-nanopore produced was characterized by mass spectrometry and single-particle cryogenic electron microscopy. In a proof-of-concept single-molecule sensing experiment, the hetero-nanopore exhibited 95% accuracy for label-free discrimination of four peptide stereoisomers with single-amino-acid structural and chiral differences in the mixtures. The customized hetero-nanopores could advance single-molecule sensing.